Getting rid of secondary sludge, or biosludge, has always been an industry issue bringing forward many problems due to its high water content and the nature of the solids contained. With these drawbacks, transportation and disposal become problematic.
As of recent, field experts are focused on improving what we currently know as traditional disposal methods like landfilling or incineration in the power boiler.
Drawbacks to the traditional approaches include:
- Offensive odor
- Water leaching from landfill sites
- Low thermal efficiency
- Potential health hazards in handling
- Overall cost of disposal
With landfills for biomass material now banned in Europe, a new approach was needed and for several mills, this was to incinerate the biosludge in the recovery boiler.
Through a proprietary system, the biosludge is hydrolyzed by mixing it with black liquor and then sent off to the concentrator for disposal in the recovery boiler.
New benefits of this approach include:
- No offensive odor
- No handling or transfer of the sludge for transport
- Higher thermal efficiency by using the multiple effect economy of the evaporators
- Incineration occurs within the recovery boiler with no real change in operation
- Lower cost solution internal to the mill operations
Current studies reveal that no significant negative impacts have been experienced in the mills that have taken on incineration of secondary sludge within the recovery boiler.
For more of an in-depth look at the recovery boiler system read our recent white paper. The analysis includes an overview of the secondary sludge hydrolysis process, detailed benefits of hydrolyzing and disposing of sludge in the recovery boiler, user experience, and additional links and information on Valmet Automation products for wastewater handling.
Valmet has over 40 years of experience in the boiler system industry. Our skilled team of industry experts can help improve your handling and disposal of secondary sludge needs.
For immediate inquiries please contact us today.